The present invention relates to a resistor device for controlling a rotational speed of a motor, and more particularly, to a resistor device for controlling a rotational speed of a motor having an improved resistor for controlling the rotational speed of the motor and having a circuit open means for preventing a burning damage of the motor.
Generally, a resistor circuit for a resistor is used to control the rotational speed of a motor. However, a resistor circuit provided to a conventional resistor is made to a structure which is silk-printed by an ink on a resin base plate. However, a problem exists that when a shock is applied to a resistor, the resin base plate formed with the resistor circuit may be readily damaged or deformed.
Additionally, a conventional resistor forms a structure directly to a resistor circuit having a short-circuit means for preventing damage to a motor by cutting off current applied to the motor side when an overload occurs due to a mechanical defect in the motor. Accordingly, a problem exists when thermal radiation of the resistor circuit is not sufficiently carried out at a portion connected to the open-circuit means. Furthermore, there has also been a problem when a by-product, such as residue produced by the fusing of the open-circuit means, becomes adhered to the resistor circuit.